In the brake yoke of disc brakes, the brake pad units are normally supported in such a way within a space, that they are prevented from rotating together with the brake disc. When the brake pad unit has worn down and the brake disc at the same time has been reduced in thickness, it may, however, occur that the brake pad unit, when almost completely worn out, slips out of its position and rotates with the disc. This may imply that the braking function is completely lost or that a complete locking of the brake disc occurs. In certain vehicles, transverse pins are provided which extend through holes, in the brake pad unit and keeps the unit in position. This construction may, however, gradually corrode and as time goes by imply jamming which, when bigger dimensions are concerned such as with disc brakes for heavy vehicles, may result in difficulties during maintenance.
One problem which is associated with a commonly occurring brake system for heavy vehicles is that the actuators, which diplace the brake pad units between braking and released position, exhibit portions at their ends which in certain conditions, e.g. when adjusting for the gradual wear of the brake pad units, are affected by torsional forces, which may cause damage to e.g. enclosing bellows and the like.
From the U.S. Pat. No. 3,162,271, it is previously known to arrange coupling means, between actuators and brake pad units in the form of T-shaped grooves and correponding pins on the actuators intended to interact with the grooves. By means of this interaction, a mutual transfer of the relative position of the actuators and the brake pad units is ensured, for instance by means of the brake pad units being brought to a released position by means of the return movement of the actuators. Since the pins, however, are completely rotationally symmetric, the end portions of the actuators will not become locked against rotation by means of the brake pad units. Consequently, this does not offer any solution to the above-mentioned problem.